package com.ahm.server.utils;

import io.jsonwebtoken.Claims;
import io.jsonwebtoken.Jwts;
import io.jsonwebtoken.SignatureAlgorithm;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.security.core.userdetails.UserDetails;
import org.springframework.stereotype.Component;

import java.util.Date;
import java.util.HashMap;
import java.util.Map;

@Component
public class JwtTokenUtil {
    private static final String CLAIM_KEY_USERNAME = "sub";
    private static final String CLAIM_KEY_CREATED = "created";
    @Value("${jwt.secret}")
    private String secret;
    @Value("${jwt.expiration}")
    private Long expiration;
    /**
    * 根据负载生成JWT Token
    *
    * @param claims
    * @return
    */
    private String generateToken(Map<String, Object> claims) {
        return Jwts.builder()
        .setClaims(claims)
        .setExpiration(generateExpirationDate())
        .signWith(SignatureAlgorithm.HS256, secret)
        .compact();
    }
    /**
    * 从token中获取JWT中的负载
    *
    * @param token
    * @return
    */
    private Claims getClaimsFromToken(String token) {
        Claims claims = null;
        try {
            claims = Jwts.parser()
            .setSigningKey(secret)
            .parseClaimsJws(token)
            .getBody();
        } catch (Exception e) {
             e.printStackTrace();
        }
        return claims;
    }
    /**
    * 生成token过期时间
    *
    * @return
    */
    private Date generateExpirationDate() {
    return new Date(System.currentTimeMillis() + expiration * 1000);
    }
    /**
    * 从token中获取过期时间
    *
    * @param token
    * @return
    */
    private Date getExpiredDateFromToken(String token) {
    Claims claims = getClaimsFromToken(token);
    return claims.getExpiration();
    }
    /**
    * 判断token是否失效
    *
    * @param token
    * @return
    */
    private boolean isTokenExpired(String token) {
        Date expiredDate = getExpiredDateFromToken(token);
        return expiredDate.before(new Date());
    }
    /**
    * 从token中获取登录用户名
    *
    * @param token
    * @return
    */
    public String getUserNameFormToken(String token) {
        String username;
        try {
        Claims claims = getClaimsFromToken(token);
        username = claims.getSubject();
        } catch (Exception e) {
        username = null;
        }
        return username;
    }
    /**
    * 验证token是否有效
    *
    * @param token
    * @param userDetails
    * @return
    */
    public boolean validateToken(String token, UserDetails userDetails) {
        String username = getUserNameFormToken(token);
        return username.equals(userDetails.getUsername()) && !isTokenExpired(token);
    }

    /**
    * 根据用户信息生成token
    * @param userDetails
    * @return
    */
    public String generateToken(UserDetails userDetails){
        Map<String,Object> claims = new HashMap<>();
        claims.put(CLAIM_KEY_USERNAME,userDetails.getUsername());
        claims.put(CLAIM_KEY_CREATED,new Date());
        return generateToken(claims);
    }
    /**
    * 判断token是否可以被刷新
    * @param token
    * @return
    */
    public boolean canRefresh(String token){
    return !isTokenExpired(token);
    }
    /**
    * 刷新token
    * @param token
    * @return
    */
    public String refreshToken(String token){
        Claims claims = getClaimsFromToken(token);
        claims.put(CLAIM_KEY_CREATED,new Date());
        return generateToken(claims);
    }
}